Princess Tagitsu, also known as Tagitsu-hime, is the main antagonist of Katana Maidens: Toji no Miko. She is a sentient Aradama, a hostile supernatural being of the kind that sword-wielding shrine maidens called Toji are trained to fight, and she is popularly known as the Great Aradama. Twenty years before the events of the series, she emerged and caused the Great Disaster of Sagami Bay, an incident in which she destroyed parts of Sagami Bay and the island of Enoshima. This makes her the largest and most destructive Aradama the Toji have confronted in generations.

She was born from an enormous concentration of noro, the spiritual impurity from which Aradama are formed, and this origin granted her intelligence and power far beyond those of ordinary Aradama. Unlike most of her kind, she possesses a sharp mind, can speak the human language in a deep and foreboding voice, and regards herself as a god of evil. Her personality is scheming, manipulative, and patient. Rather than relying on brute destruction alone, she operates through deception and long-term planning, and her overarching goal is the destruction of humanity.

Her history is closely tied to Yukari Origami, the leader of the Toji organization. The great Aradama attempted to emerge through Yukari but was separated from her, and after the resolution of the Kamakura Special Hazardous Waste Leakage Issue, it manifested in human form. Because of a logical contradiction in its existence, the entity split into three separate beings, each named after one of the Munakata Three Goddesses of Japanese mythology: Tagitsuhime, Takirihime, and Ichikishimahime. The original body of the great Aradama fled to the hidden world, and the three princesses came into conflict with one another, because any one of them who absorbs the other two will gain the will of the original main body and reclaim the full power of the Great Aradama.

Each of the three fragments carried a different intention left over from the original entity. Tagitsu-hime is the most aggressive of the three, driven by the desire to wipe out humans, while Takirihime carried the intention of cohabiting with humans through dominating them. Because they are simultaneously parts of the same being and rivals for supremacy, Tagitsu-hime's relationship with her sister fragments is one of competition, and their internal struggle forms a major layer of the series' conflict. Her connection to Yukari also remains central, as Yukari serves as a link to the Aradama's origin and the circumstances of its splitting.

In terms of abilities, Princess Tagitsu possesses overwhelming destructive power befitting her title as the Great Aradama, capable of devastating a coastal region in a single incident. She also displays exceptional intellect, the capacity for human speech, and the ability to assume human form. Her most distinctive ability is the splitting of her existence into multiple independent beings, each with its own will and agenda, while her true body remains hidden and protected in the hidden world, so that defeating any single fragment does not end the threat she represents.